One type of channel framing is called strut channel, which is used in the construction and electrical industries for structural support, often for supporting wiring, plumbing, or mechanical components such as air conditioning or ventilation systems. Strut channel is usually formed from metal sheet, folded over into an open channel shape with inwards-curving lips to provide additional stiffness and as a location to mount interconnecting components. The side of the strut channel opposite the open channel usually has holes of some sort in the base, to facilitate interconnection or fastening the strut to underlying building structures. The other sides (e.g., left and right sides) typically do not have any functionality. Thus, the strut channel really has only one side for mounting components on the strut.